During mining excavations in an underground mine a number of boreholes are typically dug in the end face of the mine. The boreholes are then filled with waterproofed explosives, a detonator is added to each of the boreholes and the explosives in the boreholes detonated in an appropriate sequence. The main reason waterproof explosives are used is due to water seepage that occurs into the boreholes that generally prevent the use of non waterproofed explosives. However, since non waterproofed the use of non waterproofed explosives. However, since non waterproofed explosives such as ANFO are generally such cheaper than waterproofed explosives there is clearly a need for a device and a method which would enable use of non waterproofed explosives in boreholes.